Semiconductor device with u-shaped channel and electronic apparatus including the same

ABSTRACT

A semiconductor device with U-shaped channel and electronic apparatus including the same are disclosed. the semiconductor device includes a first device and a second device opposite to each other on a substrate. The two devices each include: a channel portion vertically extending on the substrate and having a U-shape in a plan view; source/drain portions respectively located at upper and lower ends of the channel portion and along the U-shaped channel portion; and a gate stack overlapping the channel portion on an inner side of the U-shape. An opening of the U-shape of the first device and an opening of the U-shape of the second device are opposite to each other. At least a portion of the gate stack of the first device close to the channel portion and at least a portion of the gate stack of the second device close to the channel portion are substantially coplanar.

This application claims the benefit of Chinese Patent Application No.201911254752.x filed on Dec. 6, 2019, which is incorporated herein inits entirety by reference.

TECHNICAL FIELD

The present disclosure relates to the field of semiconductors, and inparticular to a semiconductor device with a U-shaped channel and anelectronic apparatus including such a semiconductor device.

BACKGROUND

With the continuous miniaturization of semiconductor devices, deviceswith various structures such as fin field effect transistors (FinFET)and multi-bridge channel field effect transistors (MBCFET) etc., havebeen proposed.

SUMMARY

However, these devices still cannot meet the requirements on increasingintegration density and enhancing device performance due to thelimitation of device structure.

In view of this, an object of the present disclosure is at leastpartially to provide, for example, a semiconductor device having aU-shaped channel and an electronic apparatus including such asemiconductor device.

According to an aspect of the present disclosure, there is provided asemiconductor device including a first device and a second deviceopposite to each other on a substrate. The first device and the seconddevice each include: a channel portion extending vertically on thesubstrate and having a U-shape in a plan view; source/drain portionsrespectively located at upper and lower ends of the channel portion andalong the U-shaped channel portion; and a gate stack overlapping thechannel portion on an inner side of the U-shape. An opening of theU-shape of the first device and an opening of the U-shape of the seconddevice are opposite to each other. At least a portion of the gate stackof the first device close to the channel portion and at least a portionof the gate stack of the second device close to the channel portion aresubstantially coplanar.

According to an aspect of the present disclosure, there is provided anelectronic apparatus including a semiconductor device as describedherein.

According to embodiments of the present disclosure, a semiconductordevice having a new structure is provided, which has advantages of, forexample, high performance and high density.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objectives, features, and advantages of the presentdisclosure will be clearer by reference to the following description ofembodiments of the present disclosure in combination with theaccompanying drawings. In the accompanying drawings:

FIGS. 1-25 schematically show some stages in the process ofmanufacturing a semiconductor device according to embodiments of thepresent disclosure, wherein FIGS. 3(a), 4, 5(a), 6(a), 9(a), 11(a),15(a), 21(a), 22(a) and 23(a) are top views, FIGS. 1, 2, 3(b), 5(b),6(b), 7(a), 7(b), 8, 9(b), 10, 11(b), 12(a), 13, 14(a), 15(b), 16(a),17(a), 18(a), 19(a), 20(a), 21(b), 22(b), 24 and 25 are sectional viewsalong respective line AA′, FIGS. 11(c), 12(b), 14(b), 15(c), 16(b),17(b), 18(b), 19(b) and 20(b) are sectional views along respective lineBB′, and FIG. 23(b) is a sectional view along respective line CC′.

Throughout the drawings, the same or similar reference signs indicatethe same or similar components.

DETAILED DESCRIPTION OF EMBODIMENTS

The embodiments of the present disclosure are described below withreference to the drawings. However, it should be understood that thesedescriptions are only exemplary and are not intended to limit the scopeof the present disclosure. In addition, commonly known structures andtechnologies are omitted in the following description to avoidunnecessarily obscuring the concepts of the present disclosure.

The drawings show various structural schematic diagrams according toembodiments of the present disclosure. These figures are not drawn toscale, and some details are enlarged and some details may be omitted forclarity of presentation. The shapes of various regions and layers aswell as the relative sizes and positional relationships thereof shown inthe figures are only exemplary. In practice, there may be deviations dueto manufacturing tolerances or technical limitations, and those skilledin the art may additionally design regions/layers having differentshapes, sizes, and relative positions as required.

In the context of the present disclosure, when a layer/an element isreferred to as being “on” another layer/element, the layer/element maybe directly on another layer/element, or there may be an intermediatelayer/element between them. In addition, if a layer/an element islocated “on” another layer/element in one orientation, the layer/elementmay be located “under” another layer/element when the orientation isreversed.

According to an embodiment of the present disclosure, there is provideda semiconductor device including a first device and a second deviceopposite to each other. The first device and the second device may bevertical semiconductor devices, having active regions arrangedvertically on a substrate (for example, in a direction substantiallyperpendicular to a surface of the substrate). A channel portion may beU-shaped in a plan view (for example, a top view observed from above thesubstrate), such that the channel portion may be in a form of a U-shapednano-sheet, and thus such a device may be called a U-shaped nano-sheetfield effect transistor (USNFET). A channel width may be increasedthrough the U-shaped channel portion. As described below, the U-shapednano-sheet may be formed by epitaxial growth, and thus it may be oneintegrated single piece and may have a substantially uniform thickness.The respective U-shapes of the first device and the second device may beopposite to each other.

The first device and the second device each may further includesource/drain portions respectively arranged at upper and lower ends ofthe channel portion. As described below, the source/drain portions ofthe first device and the second device may be defined by a same materiallayer, and thus they may be substantially coplanar (for example, theupper surfaces are substantially coplanar and/or the lower surfaces aresubstantially coplanar). The source/drain portions may be arranged alongthe channel portion, such that they may also be U-shaped in the planview. According to an embodiment, the source/drain portions may protrudetowards an inner side of the U-shape with respect to the channelportion, such that the source/drain portions and the channel portion areC-shaped in a sectional view. A protrusion extent of the source/drainportion of the first device with respect to the channel portion may besubstantially the same as a protrusion extent of the source/drainportion of the second device with respect to the channel portion.

The C-shape formed by the channel portion and the source/drain portions(i.e., an active region) may facilitate defining a space foraccommodating a gate stack. As described below, the gate stacks of thefirst device and the second device may be defined by a same materiallayer, and thus at least their end portions on a side close to thechannel portion may be substantially coplanar (for example, the uppersurfaces are substantially coplanar and/or the lower surfaces aresubstantially coplanar).

The source/drain portion may have a certain doping. For example, for ap-type device, the source/drain portion may have a p-type doping; andfor a n-type device, the source/drain portion may have a n-type doping.The doping profile of the source/drain portion may have an end portionoverlapping the gate stack to reduce an external resistance. The channelportion may have a certain doping to adjust a threshold voltage of thedevice. Alternatively, the semiconductor device may be a junctionlessdevice, in which the channel portion and the source/drain portion mayhave the same conductivity type doping. Alternatively, the semiconductordevice may be a tunneling type device, in which the source/drainportions at both ends of the channel portion may have doping typesopposite to each other.

The channel portion may include a single crystal semiconductor material.Of course, the source/drain portion may also include a single crystalsemiconductor material. For example, they may both be formed byepitaxial growth.

Such a semiconductor device may be manufactured, for example, asfollows.

According to an embodiment, a stack of a first material layer, a secondmaterial layer, and a third material layer may be provided on asubstrate. The first material layer may define a position of a lowersource/drain portion, the second material layer may define a position ofa gate stack, and the third material layer may define a position of anupper source/drain portion. The first material layer may be provided bythe substrate, such as an upper portion of the substrate. Alternatively,the first material layer, the second material layer, and the thirdmaterial layer may be sequentially formed on the substrate by, forexample, epitaxial growth. If the first material layer and the thirdmaterial layer are directly used as the source/drain portions, they maybe doped in situ while being epitaxially grown.

The stack may be patterned into a bar shape extending in a firstdirection. A first active layer may be formed on a sidewall of thebar-shaped stack. The first active layer may define the channel portion.Since being formed around the sidewall of the bar-shaped stack, thefirst active layer may be in a closed shape pattern in a plan view, suchas a ring shape, for example, a rectangular ring or a roundedrectangular ring. Two devices may be formed based on the first activelayer of this closed shape pattern, such that the channel portion ofeach device may be U-shaped. Since they may be defined by the sameactive layer, the inner sidewalls and/or outer sidewalls of the channelportions of the two devices may be substantially coplanar.

The gate stack may be formed inside the closed shape pattern. For thispurpose, an opening may be formed in the bar-shaped stack so as to leavea space on an inner side of the closed shape pattern. The opening mayalso extend substantially in the first direction, such that the abovestack has a closed shape pattern, e.g., ring-shaped. This facilitatesformation of the source/drain portion along the channel portion. Thesecond material layer may be replaced with a gate stack through theopening formed in such a manner.

In order to facilitate the formation of the source/drain portions, forexample, the source/drain portions are formed by doping the firstmaterial layer and the third material layer (in particular, in acondition that they are not doped when they are formed), or as describedbelow, the source/drain portions are formed by additionally growing asecond active layer, wherein a dummy gate may be formed first. Forexample, the second material layer may be removed by selective etchingthrough the opening, thereby leaving a space between the first materiallayer and the second material layer. A dummy gate may be formed in thisspace. The dummy gate covers a portion of the first active layer betweenthe first material layer and the second material layer.

The source/drain portions may be formed on the upper and lower sides ofthe dummy gate. For example, the source/drain portions may be formed bydoping the first material layer and the third material layer. Suchdoping may be achieved by a solid phase dopant source layer. As they maybe defined by the same material layer, the inner sidewalls and/or outersidewalls of the source/drain portions of the two devices may besubstantially coplanar. Alternatively, the first material layer and thethird material layer may be at least partially removed (or evencompletely removed, thereby exposing the first active layer), and thesecond active layer may be grown on the upper and lower sides of thedummy gate. The second active layer may be doped in situ during growth.The impurities may be activated by annealing, such that the impuritiesmay diffuse into the first active layer and overlap the end of the dummygate to a certain extent. After that, the dummy gate may be replacedwith a gate stack through a gate replacement process.

The present disclosure may be presented in various forms, someembodiments of which will be described below. In the followingdescription, the selection of various materials is involved. In additionto their functions (for example, semiconductor materials are used toform active regions and dielectric materials are used to form electricalisolation), etching selectivity is also considered for select materials.In the following description, the required etching selectivity may ormay not be indicated. It should be clear to those skilled in the artthat when etching a certain material layer is mentioned below, if it isnot mentioned that other layers are also etched or the figures do notshow that other layers are also etched, then such etching may beselective, and the material layer may have an etching selectivity withrespect to other layers exposed to the same etching recipe.

FIGS. 1 to 25 schematically illustrate some stages in the process ofmanufacturing a semiconductor device according to an embodiment of thepresent disclosure.

As shown in FIG. 1, there is provided a substrate 1001 (an upper portionof which may form the above first material layer). The substrate 1001may be a substrate in various forms, including but not limited to asemiconductor material substrate such as a bulk Si substrate, asemiconductor-on-insulator (SOI) substrate, a compound semiconductorsubstrate such as a SiGe substrate, or the like. In the followingdescription, for convenience of description, a bulk Si substrate istaken as an example for description. Here, a silicon wafer is providedas the substrate 1001.

In the substrate 1001, a well region may be formed. If a p-type deviceis to be formed, the well region may be a n-type well; and if a n-typedevice is to be formed, the well region may be a p-type well. The wellregion may be formed, for example, by injecting a correspondingconductivity type dopant (a p-type dopant such as B or In, or a n-typedopant such as As or P) into the substrate 1001 and then performingthermal annealing. There are many ways to create such a well region inthe art, which will not be repeated here.

In this embodiment, an example is described in which a p-type device anda n-type device are formed at the same time, and the p-type device andthe n-type device are adjacent to each other (a complementary metaloxide semiconductor (CMOS) configuration can then be formed), therebyforming adjacent n-type and p-type wells. However, the presentdisclosure is not limited to this. For example, devices having the sameconductivity type may be formed. Alternatively, devices having differentconductivity types may be formed, but the p-type device is formed in acertain region and the n-type device is formed in another region.

On the substrate 1001, a second material layer 1003 and a third materiallayer 1005 may be formed by, for example, epitaxial growth. The secondmaterial layer 1003, having a thickness selected from, for example,about 20 nm-50 nm, may be used to define a position of a gate stack. Thethird material layer 1005, having a thickness selected from, forexample, about 20 nm-200 nm, may be used to define a position of anupper source/drain portion.

The substrate 1001 and the layers formed thereon may have an etchingselectivity with respect to each other. For example, in a condition thatthe substrate 1001 is a silicon wafer, the second material layer 1003may include SiGe (for example, an atomic percentage of Ge selected fromabout 10%-30%), and the third material layer 1005 may include Si.

As shown in FIG. 2, in the substrate 1001, an active region may bedefined by an isolation portion 1007, such as a shallow trench isolation(STI). For example, the isolation portion 1007 may surround each activeregion. The isolation portion 1007 may be formed between the n-type welland the p-type well, thereby defining the respective active regions forthe p-type device and the n-type device. Here, the isolation portion1007 may pass through the second material layer 1003 and the thirdmaterial layer 1005.

According to the embodiment, a spacer pattern transfer technology isused in the following patterning. In order to form a spacer, a mandrelpattern may be formed. Specifically, a layer 1011 used for the mandrelpattern may be formed on the third material layer 1005 by, for example,deposition. For example, the layer 1011 used for the mandrel pattern mayinclude amorphous silicon or polysilicon, having a thickness selectedfrom about 50 nm-150 nm. In addition, for better etching control, anetching stop layer 1009 may be formed first by, for example, deposition.For example, the etch stop layer 1009 may include oxide (for example,silicon oxide) having a thickness selected from about 2 nm-10 nm.

On the layer 1011 used for the mandrel pattern, a hard mask layer 1013may be formed by, for example, deposition. For example, the hard masklayer 1013 may include nitride (for example, silicon nitride) having athickness selected from about 50 nm-100 nm.

The layer 1011 used for the mandrel pattern may be patterned into amandrel pattern. For example, as shown in FIGS. 3(a) and 3(b), aphotoresist 1015 may be formed on the hard mask layer 1013, and it ispatterned by photolithography to a bar extending along a first direction(a horizontal direction in the figures). Here, the bar-shaped pattern isshown as extending on opposite sides of the isolation portion 1007across the isolation portion 1007, such that two devices may be definedsubsequently.

In the embodiment of FIG. 3(a), the portions of the bar-shaped patternon the opposite sides of the isolation portion 1007 may havesubstantially the same length, such that the channel portions of the twodevices obtained subsequently may have substantially the same channelwidth. However, the present disclosure is not limited to this. Forexample, according to performance requirements of the two devices in thedesign, the extension lengths of the bar-shaped pattern on the oppositesides of the isolation portion 1007 may be different.

In the embodiment of FIG. 3(a), the bar-shaped pattern is shown to havea rectangular shape in a top view. However, the present disclosure isnot limited to this. According to other embodiments, the bar-shapedpattern may have another shape, such as an elliptical shape, a roundedrectangular shape (see FIG. 4), or the like.

As shown in FIGS. 5(a) and 5(b), the photoresist 1015 may be used as anetching mask. A selective etching is sequentially performed to the hardmask layer 1013 and the layer 1011 used for the mandrel pattern using,for example, reactive ion etching (RIE), and the pattern of thephotoresist is transferred to the hard mask layer 1013 and the layer1011 used for the mandrel pattern. The etching may stop at the etchingstop layer 1009. Afterwards, the photoresist 1015 may be removed.

As shown in FIGS. 6(a) and 6(b), a spacer 1017 may be formed on the sidewall of the mandrel pattern 1011. For example, a layer of nitride havinga thickness selected from about 10 nm-50 nm may be deposited in asubstantially conformal manner, and then an anisotropic etching such asRIE (which may be stopped at the etching stop layer 1009) is performedto the deposited nitride layer along a vertical direction so as toremove its lateral extension portion and leave its vertical extensionportion, thereby obtaining the spacer 1017. The spacer 1017 may then beused to define the position of the active region of the device.

As shown in the top view of FIG. 6(a), the spacer 1017 may be formedaround the side wall of the mandrel pattern 1011 so as to be annular. Inthis embodiment, the spacer 1017 and the hard mask layer 1013 includethe same material (nitride), and thus they may appear as one piece inthe top view of FIG. 6(a).

As shown in FIG. 7(a), the hard mask layer 1013 and the spacer 1017 maybe used to pattern the third material layer 1005, the second materiallayer 1003 and the upper portion (the first material layer) of thesubstrate 1001 into a ridge structure. For example, the hard mask layer1013 and the spacer 1017 may be used as etching masks, wherein selectiveetching is sequentially performed to each layer by, for example, RIE,and the pattern is transferred to a lower layer. The etching may enterthe well region of the substrate 1001. Thus, on the opposite sides ofthe isolation portion 1007, the upper portion of the substrate 1001, thesecond material layer 1003 and the third material layer 1005 mayrespectively form ridge structures extending in the first direction.

A first active layer may be formed on the sidewall of the ridgestructure so as to subsequently define the channel portion. For theconvenience of the following patterning, the portion of the first activelayer serving as the channel portion may be formed under the spacer 1017(it may be minimized to provide a protective layer for the channelportion in the following patterning). For example, the ridge structuremay be etched back such that its outer peripheral side wall is recessedlaterally with respect to an outer peripheral side wall of the spacer1017. In order to control the etching depth, an atomic layer etching(ALE) may be used. Then, a first active layer 1019 may be formed on thesidewall of the ridge structure by, for example, selective epitaxialgrowth. Due to the selective epitaxial growth, the first active layer1019 may be formed on the vertical sidewall of the ridge structure andthe surface of the substrate 1001. The first active layer 1019 may thendefine the channel portion, having a thickness selected from, forexample, about 3 nm-15 nm. According to an embodiment of the presentdisclosure, the thickness of the first active layer 1019 (which is thenused as a channel portion) may be determined by an epitaxial growthprocess, and thus the thickness of the channel portion may be bettercontrolled.

On the opposite sides of the isolation portion 1007, the verticalportion of the first active layer 1019 may respectively form U shapescorresponding to the spacer.

In FIG. 7(a), the sidewall of the portion of the first active layer 1019on the vertical sidewall of the ridge structure is shown to besubstantially flush with the sidewall of the spacer 1017. This may beachieved by controlling the amount of etch-back and the thickness of theepitaxial growth to be substantially the same. However, the presentdisclosure is not limited to this. For example, the sidewall of theportion of the first active layer 1019 on the vertical sidewall of theridge structure may be recessed with respect to the sidewall of thespacer 1017, or even may protrude.

Due to such epitaxial growth, the material of the first active layer1019 may be appropriately selected according to performance requirementsof the device in the design. For example, the first active layer 1019may include various semiconductor materials, such as Si, Ge, SiGe, GaAs,InGaAs, etc.

In the embodiment of FIG. 7(a), first active layer portions 1019 on theopposite sides of the isolation portion 1007 may have substantially thesame characteristics (for example, material, size, etc.). However, thepresent disclosure is not limited to this. For example, according toperformance requirements of the two devices on the opposite sides of theisolation portion 1007 in the design, the first active layer portions1019 on the opposite sides of the isolation portion 1007 may have adifferent characteristic, such as different materials and/or sizes. Thiscan be achieved by shielding the other device region when the firstactive layer is grown in one device region. For example, FIG. 7(b) showsthat first active layer portions 1019 a and 1019 b on the opposite sidesof the isolation portion 1007 may have different thicknesses. Inaddition, for a p-type device, the first active layer 1019 a may includeSi, SiGe, Ge, etc.; and for a n-type device, the first active layer 1019b may include Si, InGaAs, InP, or other III-V compound semiconductor.

In order to facilitate subsequent manufacturing of an electrical contactto the lower source/drain portion, a contact region may be formed in thelaterally extending portion of the first active layer 1019. For example,ion implantation may be used to inject dopants into the laterallyextending portion of the first active layer 1019. The conductivity typeof the dopants may be the same as the conductivity type of the contactportion subsequently formed. For example, for a p-type device, p-typedopants such as B, BF₂ or In may be injected with a concentrationselected from about 1E19-1E21 cm⁻³; and for a n-type device, n-typedopants such as P or As may be injected with a concentration selectedfrom about 1E19-1E21 cm⁻³. The laterally extending portion of the firstactive layer 1019 containing the dopants (which may be activated by asubsequent annealing process) may form a contact region (see 1019 c inFIG. 8). Due to the existence of the spacer 1017, ion implantation maynot substantially affect the vertical portion (which is subsequentlyformed to be a channel portion) of the first active layer 1019.

In order to further reduce the contact resistance, silicide may also beformed on the laterally extending portion of the first active layer1019. For example, a shielding layer (for example, oxynitride in theform of a spacer) may be used to shield the vertically extending portionof the first active layer 1019, then a metal such as NiPt, Co, Ni, Ti,etc. is deposited on the laterally extending portion of the first activelayer 1019, and an annealing process is performed to make the metalreact with the laterally extending portion of the first active layer1019, thereby generating silicide. Afterwards, the unreacted metal maybe removed, and the shielding layer may be removed.

As shown in FIG. 8, an isolation layer 1021 may be formed around theridge structure on the sidewall of which the first active layer 1019 isformed. For example, an oxide layer that completely covers the ridgestructure may be formed by deposition on the substrate 1001, andplanarization processing such as chemical mechanical polishing (CMP)(CMP may be stopped at the mandrel pattern 1011) is performed to thedeposited oxide layer to form an isolation layer 1021.

As shown in FIGS. 9(a) and 9(b), the mandrel pattern 1011 may be removedby selective etching such as wet etching using TMAH solution or dryetching using RIE. In this way, an annular spacer 1017 is remained onthe ridge structure. As shown in the top view of FIG. 9(a), the spacer1017 respectively defines two U-shapes opposite to each other on theopposite sides of the isolation portion.

As shown in FIG. 10, the stop layer 1009, the third material layer 1005,the second material layer 1003 and the upper portion of the substrate1001 may be selectively etched by using the spacer 1017 as an etchingmask using, for example RIE. The etching may be performed into the wellregion of the substrate 1001. In this way, on the opposite sides of theisolation portion, the third material layer 1005, the second materiallayer 1003, and the upper portion of the substrate 1001 respectivelyform U shapes corresponding to the spacer 1017.

Of course, the formation of a U-shaped pattern is not limited to thespacer pattern transfer technology, and may also be performed byphotolithography using photoresist or the like.

Here, for the purpose of epitaxial growth, the second material layer1003 for defining the position of the gate stack includes asemiconductor material, which is inconvenient in the followingprocessing to the source/drain portion. For this reason, the secondmaterial layer 1003 may be replaced with a dielectric material to form adummy gate to facilitate subsequent processing to the source/drainportions.

For example, as shown in FIGS. 11(a) to 11(c), the second material layer1003 (SiGe in this example) may be removed by selective etching withrespect to the first active layer 1019, the substrate 1001 and the thirdmaterial layer 1005 (they are all Si in this example). Then, as shown inFIGS. 12(a) and 12(b), a dummy gate 1023 may be formed in the remainingspace due to the removal of the second material layer 1003 below thespacer 1017. The dummy gate 1023 may be formed by deposition and thenetched-back. For example, the dummy gate 1023 may include a material,such as SiC, having etching selectivity with respect to the firstmaterial layer, the third material layer and the first active layer.

According to an embodiment, the contact region 1019 c may be thickenedto reduce contact resistance from the subsequently formed contactportion to the lower source/drain portion. As shown in FIG. 13, a dopantmay be injected into the substrate 1001 on the inner side of the spacer1017 by ion implantation. The conductivity type of the dopant may be thesame as the conductivity type of the lower end contact portion formedsubsequently. For example, for a p-type device, p-type dopant such as B,BF₂ or In may be injected with a concentration selected from about1E19-1E21 cm⁻³; and for a n-type device, n-type dopant such as P or Asmay be injected with a concentration selected from about 1E19-1E21 cm⁻³.Here, the p-type device and the n-type devices may be injectedseparately. When processing is performed to the devices of one type, ashielding layer may be used to shield the region where the devices ofanother type are located. In the substrate 1001 on the inner and outersides of the spacer 1017, the dopants injected twice in succession maybe connected to each other by annealing, and they are shown together as1019 c′ and 1019 d′ in the figure.

Afterwards, the source/drain portion may be formed.

In the following embodiment, the first material layer and the thirdmaterial layer are doped by a solid phase dopant source layer to formthe source/drain portion. In order to facilitate the formation of asolid phase dopant source layer on the inner side of the spacer 1017,the isolation portion 1007 (see FIG. 13) that currently occupies aconsiderable space on the inner side of the spacer 1017 may be recessedto a certain extent to release a certain space and facilitate filmfilling.

In order to avoid too much influence on the exposed surface of thesubstrate 1001 when the isolation portion 1007 is recessed, as shown inFIGS. 14(a) and 14(b), a dielectric material 1007′ (here, oxide) whichis the same as the isolation portion 1007 may be filled by, for example,deposition and then planarization (which is stopped at the spacer 1017)on the inner side of the spacer 1017.

According to an embodiment, before the dielectric material 1007′ isfilled, a silicide may be formed on the exposed surface of thesubstrate. For example, a shielding layer (for example, oxynitride inthe form of a spacer) may be used to shield the sidewalls of the firstmaterial layer, the dummy gate and the third material layer, then ametal such as NiPt, Co, Ni, Ti, etc. is deposited on the exposed surfaceof the substrate 1001, and annealing processing is performed to make themetal react with the exposed surface of the substrate 1001, therebygenerating silicide. Afterwards, the unreacted metal may be removed. Theshielding layer may be removed in the subsequent etching process to thedielectric material 1007′.

Then, as shown in FIGS. 15(a) to 15(c), the isolation layer 1021 on theouter side of the spacer 1017 may be shielded by a shielding layer suchas a photoresist 1025 to expose the dielectric material 1007′ on theinner side of the spacer 1017. The exposed dielectric material 1007′ andthe isolation portion 1007 that may be subsequently exposed, areselectively etched by, e.g., RIE. In the condition that the isolationlayer 1021 on the outer side of the spacer 1017 has an etchingselectivity with respect to the dielectric material 1007′ on the innerside of the spacer 1017 and the isolation portion 1007, the photoresist1025 may not be required. Here, on the inner side of the spacer 1017,the dielectric material 1007′ may be substantially completely removed toexpose the surface of the substrate 1001, but a portion of the isolationportion 1007 remains. The remaining isolation portion 1007 may preventan undesired short circuit when the source/drain portion is formedsubsequently, and may prevent a np junction below the isolation portion1007 from being damaged. Afterwards, the photoresist 1025 may beremoved.

FIG. 15(b) shows that the top surface of the remaining isolation portion1007 is approximately flush with the surface of the substrate 1001.However, the present disclosure is not limited to this. For example, thetop surface of the remained isolation portion 1007 may be (slightly)higher or lower than the surface of the substrate 1001.

As shown in FIGS. 16(a) and 16(b), a solid phase dopant source layer maybe formed on the structure (with the photoresist being removed) shown inFIGS. 15(a) to 15(c) by, for example, deposition. Here, solid-phasedopant source layer portions may be respectively formed for a p-typedevice and a n-type device. For example, a shielding layer (for example,oxynitride having a thickness selected from about 2 nm-10 nm, not shown)may be used to shield the n-type device region (the region above thep-type well region). Then, a solid phase dopant source layer 1027 forthe p-type device may be formed. The solid phase dopant source layer1027 may extend on the shielding layer. A diffusion barrier layer 1029(for example, oxynitride having a thickness selected from about 2 nm-5nm) may be formed on the solid phase dopant source layer 1027. Theshielding layer on the n-type device region as well as the solid phasedopant source layer 1027 and the diffusion barrier layer 1029 thereonmay be removed, such that the solid phase dopant source layer 1027remains on the p-type device region (the region above the n-type wellregion), the diffusion barrier layer 1029 remains on the solid phasedopant source layer 1027, and the n-type device region is exposed.Afterwards, a solid phase dopant source layer 1031 for the n-type devicemay be formed.

For example, solid phase dopant source layers 1027, 1031 may be oxidescontaining dopants. The dopants contained in the solid phase dopantsource layers 1027, 1031 may be used to dope the source/drain portionand the exposed surface of the substrate 1001, and thus they may havethe same conductivity type as the source/drain portion to be formed. Forexample, for a p-type device, the solid phase dopant source layer 1027may contain p-type dopant such as B or In; and for a n-type device, thesolid phase dopant source layer 1031 may contain n-type dopant such as Por As. The concentration of the dopants of the solid phase dopant sourcelayers 1027, 1031 may be selected from about 0.01%-5%. The dopants inthe solid phase dopant source layers 1027 and 1031 may be driven intothe first material layer and the third material layer by annealingtreatment to form a source/drain portion S/D-p for the p-type device anda source/drain portion S/D-n for the n-type device. In the source/drainportions S/D-p and S/D-n, the concentration of the dopants may beselected from about 1E19-1E21 cm⁻³. Afterwards, the solid phase dopantsource layers 1027, 1031 and the diffusion barrier layer 1029 may beremoved.

According to an embodiment, the dopants may also be driven into thefirst active layer 1019, and desirably into an end of the portion of thefirst active layer 1019 covered by the dummy gate 1023 (defining thechannel portion), such that the doping profile of the source/drainportion may have some overlap with the dummy gate 1023 (and the gatestack formed subsequently), which helps to reduce external resistance.

In this example, the dopants may be driven into the first active layer1019 from the upper and lower sides of the dummy gate via the firstmaterial layer and the third material layer, respectively. Therefore,the extent to which the dopants are driven into the first active layer(more specifically, the portion of the first active layer covered by thedummy gate) may be substantially the same at the upper and lowersurfaces of the dummy gate. More specifically, the distance between thedoped interface between the upper source/drain portion and the channelportion and the upper surface of the dummy gate may be substantiallyequal to the distance between the doped interface between the lowersource/drain portion and the channel portion and the lower surface ofthe dummy gate. The distance may be selected from about 2 nm-10 nm, forexample. In addition, the distance may remain substantially unchangedalong the longitudinal extension direction of the dummy gate. Inaddition, the distance may be substantially the same on both sides ofthe isolation portion 1007. Therefore, the interface between thesource/drain portion S/D-p and the channel portion in the p-type deviceregion and the interface between the source/drain portion S/D-n and thechannel portion in the n-type device region may be substantiallycoplanar.

In this example, the first material layer is provided by the upperportion of the substrate 1001. However, the present disclosure is notlimited to this. For example, the first material layer may also be anepitaxial layer on the substrate 1001. In this case, the first materiallayer and the third material layer may be doped in situ during epitaxy,instead of being doped using a solid phase dopant source layer.

In addition, in this example, the source/drain portion S/D is formeddirectly based on the first material layer and the third material layer.However, the present disclosure is not limited to this.

For example, as shown in FIGS. 17(a) and 17(b), the first material layerand the third material layer may be at least partially etched back byselective etching. Etching back may be performed into the first activelayer, but it is desirable to remain a certain thickness ofsemiconductor layer (the first material layer, the third material layer,or the first active layer) on the upper and lower sides of the dummygate to serve as a seed layer for subsequent epitaxial growth.Afterwards, second active layers 1033 and 1037 may be formed on theupper and lower sides of the dummy gate by selective epitaxial growth.The second active layers 1033, 1037 may be doped in-situ during growth.In addition, an annealing treatment may be performed to activate thedopants, and the dopants may be driven into the first active layer, suchthat the doping profile of the source/drain portion as described abovemay have some overlap with the dummy gate 1023 (and the gate stackformed subsequently).

For a p-type device and a n-type device, the materials of the secondactive layers 1033 and 1037 may be different. At this time, the secondactive layers may be grown separately for the p-type device and then-type device. For example, a shielding layer (for example, oxynitridehaving a thickness selected from about 2 nm-10 nm, not shown) may beused to shield the n-type device region, then the first material layerand the third material layer of the p-type device region may be etchedback, and a second active layer 1033 for the p-type device is grown.Then, a shielding layer 1035 (for example, oxynitride) is used to shieldthe p-type device region where the second active layer 1033 has beengrown, the shielding layer on the n-type device region is removed toexpose the first material layer and the third material layer in then-type device region, and they are also etched back and grown to form asecond active layer 1037 for the n-type device. Afterwards, theshielding layer 1035 may be removed.

Here, the material of the second active layers 1033, 1037 may beselected to be, for example, a semiconductor material having a differentlattice constant from the first active layer (Si in this example), suchthat a stress may be applied to the channel region subsequently formedin the first active layer to enhance device performance. For example,for a p-type device, the second active layer 1033 may include SiGe (theatomic percentage of Ge selected from, for example, about 0-75%) suchthat a compressive stress is applied; and for a n-type device, thesecond active layer 1037 may include Si:C (the atomic percentage of Cselected from, for example, about 0-3%) such that a tensile stress isapplied.

In addition, the grown second active layer 1033 may appear as a shapethat tapers toward an inner side in a sectional view, for example, asubstantially trapezoidal shape. This helps reduce the capacitancebetween the source/drain portion and the gate stack.

Next, a replacement gate process may be performed to replace the dummygate with a gate stack.

As shown in FIGS. 18(a) and 18(b), an isolation layer 1038 may be formedon the inner side of the spacer 1017. For example, a dielectric materialsuch as an oxide may be deposited to completely fill the space on theinner side of the spacer 1017. Then, a planarization processing, such asCMP, may be performed to the deposited dielectric material, and the CMPmay be stopped at the spacer 1017. Where the deposited dielectricmaterial and the isolation layer 1021 contain the same material such asoxide, a shielding layer such as photoresist 1037 may be formed toshield the isolation layer 1021 on the outer side of the spacer 1017.Afterwards, the deposited dielectric material may be etched back.Dielectric material having a certain thickness remains on the bottom ofthe space on the inner side of the spacer 1017 to form an isolationlayer 1038. The isolation layer 1038 may shield the lower source/drainportion. For example, the top surface thereof is (slightly) higher thanthe bottom surface of the dummy gate, but the sidewall of the dummy gateis fully exposed for subsequent removal of the dummy gate and fillingthe gate stack. Afterwards, the photoresist 1037 may be removed.

FIGS. 19(a) and 19(b) show an embodiment of forming the isolation layer1038 where the second active layers 1033, 1037 are additionally formedas shown in FIGS. 17(a) and 17(b).

Then, as shown in FIGS. 20(a) and 20(b), the dummy gate may be removedby selective etching, and a gate stack may be formed on the inner sideof the spacer 1017. For example, a gate dielectric layer 1039 may beformed in a substantially conformal manner by deposition, and theremaining space may be filled with a gate conductor layer 1041 p usedfor the p-type device. A planarization processing, such as CMP, may beperformed to the filled gate conductor layer 1041 p, and the CMP may bestopped on the spacer 1017. Then, the gate conductor layer 1041 p may beetched back, and the etching back may be stopped on the gate dielectriclayer 1039. In this way, the gate conductor layer 1041 p remains in thespace below the spacer 1017 remained due to the removal of the dummygate.

Then, as shown in FIGS. 21(a) and 21(b), a shielding layer (not shown)may be used to shield the p-type device region, and to expose the n-typedevice region, and the gate conductor layer 1041 p on the n-type deviceregion is removed by selective etching. Afterwards, a gate conductorlayer 1041 n used for the n-type device may be filled into the space onthe inner side of the spacer 1017. The planarization processing, such asCMP, may be performed to the filled gate conductor layer 1041 n, and theCMP may be stopped on the spacer 1017. Then, the gate conductor layer1041 n may be etched back such that its top surface is lower than thetop surface of the original dummy gate to reduce the capacitance betweenthe source/drain portion and the gate stack.

For example, the gate dielectric layer 1039 may include a high-k gatedielectric such as HfO₂, having a thickness selected from, for example,about 1 nm-5 nm. Before the high-k gate dielectric is formed, aninterface layer may also be formed, for example, an oxide formed by anoxidation process or deposition such as atomic layer deposition (ALD),having a thickness selected from about 0.3 nm-1.5 nm. The gate conductorlayer 1041 p is used for a p-type device, and may include a workfunction adjusting metal such as TiN, TaN, etc., and a gate conductivemetal such as W. Similarly, the gate conductor layer 1041 n may includea work function adjusting metal such as TiN, TaN, TiAlC, etc., and agate conductive metal such as W.

In this example, the p-type device and the n-type device have the samegate dielectric layer 1039. However, the present disclosure is notlimited to this. For example, the p-type device and the n-type devicemay have different gate dielectric layers. When different materials areused for devices of different types, they may be processed separately.As described above, when processing is performed to devices of one type,a shielding layer may be used to shield the region where devices ofanother type are located. Their processing orders may be exchanged.

In this manner, an end portion of the formed gate stack is embedded inthe space where the previous dummy gate is located, and overlaps withthe first active layer, thereby defining a channel portion in the firstactive layer. In addition, in the plan view, the gate stack may coveralmost the entire space on the inner side of the spacer 1017 on theisolation layer 1038.

According to the device design, as shown in FIGS. 22(a) and 22(b), thegate conductor layer 1041 n may be disconnected between the two devicesby, for example, photolithography.

So far, the fabrication of the basic structure of the device iscompleted. Subsequently, various contacts, interconnecting structures,etc. may be fabricated.

For example, as shown in FIGS. 23(a) and 23(b), a dielectric materialsuch as oxide (shown together with the previous isolation layer as1021′) may be filled into the space on the inner side of the spacer 1017by, for example, deposition and then planarization. As shown in FIG.23(b), the previously formed isolation portion 1007 still remains belowthe spacer 1017. Then, as shown in FIG. 24, a contact hole may be formedin the isolation layer 1021′, and a conductive material such as metalmay be filled in the contact hole to form a contact portion 1043. Thecontact portion 1043 may include a contact portion to the source/drainportion of each device and a contact portion to the gate conductor.

FIG. 25 shows a situation where the gate conductor layer between thep-type device and the n-type device is not disconnected. In thissituation, a common contact portion to the gate conductor layers of boththe p-type device and the n-type device may be formed.

The semiconductor device according to the embodiments of the presentdisclosure may be applied to various electronic apparatuses. Forexample, an integrated circuit (IC) may be formed based on such asemiconductor device, thereby constructing an electronic apparatus.Therefore, the present disclosure also provides an electronic apparatusincluding the above semiconductor device. The electronic apparatus mayfurther include components such as a display screen matched with anintegrated circuit and a wireless transceiver matched with an integratedcircuit. Such electronic apparatus include smart phones, computers,tablet computers (PCs), wearable smart devices, mobile power supplies,and so on.

According to an embodiment of the present disclosure, there is provideda method of manufacturing a system on chip (SoC). The method may includethe method described above. Specifically, a variety of devices may beintegrated on a chip, wherein at least some of the devices aremanufactured according to the method of the present disclosure.

In the above description, the technical details such as patterning andetching of each layer are described in detail. However, those skilled inthe art should understand that various technical means may be used toform layers, regions, etc. of desired shapes. In addition, in order toform a same structure, those skilled in the art may also design a methodthat is not completely the same as the method described above. Inaddition, although the respective embodiments are described aboveseparately, this does not mean that the measures in the respectiveembodiments may not be advantageously used in combination.

Embodiments are provided according to the following clauses:

1. A semiconductor device comprising a first device and a second deviceopposite to each other on a substrate, the first device and the seconddevice each comprising:

a channel portion extending vertically on the substrate and having aU-shape in a plan view;

source/drain portions respectively located at upper and lower ends ofthe channel portion and along the U-shaped channel portion; and

a gate stack overlapping the channel portion on an inner side of theU-shape,

wherein an opening of the U-shape of the first device and an opening ofthe U-shape of the second device are opposite to each other, and

wherein at least a portion of the gate stack of the first device closeto the channel portion and at least a portion of the gate stack of thesecond device close to the channel portion are substantially coplanar.

2. The semiconductor device according to clause 1, wherein at least oneof the followings is true:

an upper source/drain portion of the first device and an uppersource/drain portion of the second device are substantially coplanar;

a lower source/drain portion of the first device and a lowersource/drain portion of the second device are substantially coplanar.

3. The semiconductor device according to clause 1, wherein,

the U-shape of the first device comprises a first arm and a second armopposite to each other, and

the U-shape of the second device comprises a third arm and a fourth armopposite to each other,

wherein the first arm and the third arm extend oppositely in asubstantially same direction, and the second arm and the fourth armextend oppositely in a substantially same direction.

4. The semiconductor device according to clause 3, wherein the first armand the third arm extend along a substantially same straight line, andthe second arm and the fourth arm extend along a substantially samestraight line.5. The semiconductor device according to clause 1, wherein at least oneof the following is true:

an interface between the upper source/drain portion and the channelportion of the first device and an interface between the uppersource/drain portion and the channel portion of the second device aresubstantially coplanar; and

an interface between the lower source/drain portion and the channelportion of the first device and an interface between the lowersource/drain portion and the channel portion of the second device aresubstantially coplanar.

6. The semiconductor device according to clause 1, wherein at least oneof the followings is true:

an inner sidewall of the channel portion of the first device and aninner sidewall of the channel portion of the second device aresubstantially coplanar; and

an outer sidewall of the channel portion of the first device and anouter sidewall of the channel portion of the second device aresubstantially coplanar.

7. The semiconductor device according to clause 1, wherein at least oneof the followings is true:

an inner sidewall of the upper source/drain portion of the first deviceand an inner sidewall of the upper source/drain portion of the seconddevice are substantially coplanar; and

an outer sidewall of the upper source/drain portion of the first deviceand an outer sidewall of the upper source/drain portion of the seconddevice are substantially coplanar.

8. The semiconductor device according to clause 1, wherein at least oneof the followings is true:

an inner sidewall of at least an upper portion of the lower source/drainportion of the first device and at least the inner sidewall of the lowersource/drain portion of the second device are substantially coplanar;and

an outer sidewall of at least the upper portion of the lowersource/drain portion of the first device and at least the outer sidewallof the lower source/drain portion of the second device are substantiallycoplanar.

9. The semiconductor device according to clause 1, the first device andthe second device each further comprising:

a hard mask layer on an upper source/drain portion,

wherein the hard mask layers of the first device and the second deviceform a closed loop.

10. The semiconductor device according to clause 1, wherein therespective channel portions of the first device and the second devicehave a substantially same thickness along the U-shape.11. The semiconductor device according to clause 10, wherein a thicknessof the channel portion of the first device is different from that of thechannel portion of the second device.12. The semiconductor device according to clause 1, wherein thesource/drain portions of each of the first device and the second deviceprotrudes toward an inner side of the U-shape with respect to thechannel portion, such that the source/drain portions and the channelportion are of C-shape in a sectional view.13. The semiconductor device according to clause 12, wherein aprotruding extent of the source/drain portion of the first device withrespect to the channel portion is substantially the same as a protrudingextent of the source/drain portion of the second device with respect tothe channel portion.14. The semiconductor device according to clause 12, wherein an endportion of the gate stack close to the channel portion is embedded inthe C-shape.15. The semiconductor device according to clause 12, wherein thesource/drain portion has a shape that tapers toward an inner side of theU-shape in a sectional view.16. The semiconductor device according to clause 1, wherein the U-shapehas rounded corners.17. The semiconductor device according to clause 1, wherein for each ofthe first device and the second device, a distance between an dopedinterface between the upper source/drain portion and the channel portionand an upper surface of an end portion of the gate stack close to thechannel portion is substantially the same as a distance between an dopedinterface between the lower source/drain portion and the channel portionand a lower surface of the end portion of the gate stack close to thechannel portion.18. The semiconductor device according to clause 17, wherein thedistance is 2 nm-10 nm.19. The semiconductor device according to clause 17, wherein thedistance of the first device is substantially the same as the distanceof the second device.20. The semiconductor device of clause 1, wherein a doping profile ofthe source/drain portion has an end portion overlapping the gate stack.21. The semiconductor device according to clause 1, wherein the channelportion of each of the first device and the second device is formed in afirst semiconductor layer, the first semiconductor layer verticallyextends to the source/drain portion such that each of end portionslocated at the upper and lower end constitutes a portion of acorresponding source/drain portion, and the source/drain portion furthercomprises a second semiconductor layer and a third semiconductor layeron the end portions of the upper and lower end of the firstsemiconductor layer.22. The semiconductor device according to clause 21, wherein the secondsemiconductor layer and the third semiconductor layer of each of thefirst device and the second device comprise a material different fromthe first semiconductor layer.23. The semiconductor device according to clause 21, wherein a firstsemiconductor layer of the first device and a first semiconductor layerof the second device have different materials and/or thicknesses.24. The semiconductor device according to clause 21, wherein the secondsemiconductor layer and the third semiconductor layer of the firstdevice comprise a material different from the second semiconductor layerand the third semiconductor layer of the second device.25. The semiconductor device of clause 21, wherein the thirdsemiconductor layer is a portion of the substrate.26. The semiconductor device according to clause 21, wherein the firstsemiconductor layer further comprises a portion extending laterallytoward an outer side of the U-shape on the substrate.27. The semiconductor device according to clause 1, wherein the outersidewalls of at least an upper portion of the lower source/drainportion, the upper source/drain portion, and the channel portion of eachof the first device and the second device are substantially coplanar.28. The semiconductor device according to clause 1, wherein the channelportion and the source/drain portion comprise a single crystalsemiconductor material.29. The semiconductor device according to clause 1, wherein, in a planview, the gate stack is inside the U-shape.30. The semiconductor device according to clause 29, wherein, in a planview, the gate stack is throughout the inside of the U-shape.31. The semiconductor device according to clause 1, wherein the firstdevice and the second device have different conductivity types.32. The semiconductor device according to clause 31, wherein the firstdevice and the second device constitute a complementary metal oxidesemiconductor CMOS configuration.33. The semiconductor device according to clause 31, wherein gateconductors in the gate stacks of the first device and the second deviceare in contact with each other and electrically connected.34. The semiconductor device according to clause 33, wherein aconnection surface between the gate conductors of the first device andthe second device is biased toward the first device.35. The semiconductor device according to clause 31, wherein the firstdevice and the second device are respectively formed on well regions ofdifferent conductivity types in the substrate.36. The semiconductor device of clause 31, wherein the first device andthe second device comprise gate stacks having different equivalent workfunctions.37. The semiconductor device according to clause 31, wherein,

the first device is a p-type device, and the source/drain portionthereof applies a compressive stress to the channel portion, and

the second device is a n-type device, and the source/drain portionthereof applies a tensile stress to the channel portion.

38. An electronic apparatus comprising a semiconductor device accordingto clause 1.39. The electronic apparatus according to clause 38, comprising smartphones, computers, tablet computers, wearable smart devices, artificialintelligence devices, and mobile power supplies.

The above embodiments are only exemplary embodiments of the presentdisclosure, and are not used to limit the present disclosure, and theprotection scope of the present disclosure is defined by the claims.Those skilled in the art may make various modifications or equivalentsubstitutions to the present disclosure within the essence andprotection scope of the present disclosure, and such modifications orequivalent substitutions should also be regarded as falling within theprotection scope of the present disclosure.

What is claimed is:
 1. A semiconductor device comprising a first deviceand a second device opposite to each other on a substrate, the firstdevice and the second device each comprising: a channel portionextending vertically on the substrate and having a U-shape in a planview; source/drain portions respectively located at upper and lower endsof the channel portion and along the U-shaped channel portion; and agate stack overlapping the channel portion on an inner side of theU-shape, wherein an opening of the U-shape of the first device and anopening of the U-shape of the second device are opposite to each other,and wherein at least a portion of the gate stack of the first deviceclose to the channel portion and at least a portion of the gate stack ofthe second device close to the channel portion are substantiallycoplanar.
 2. The semiconductor device according to claim 1, wherein: anupper source/drain portion of the first device and an upper source/drainportion of the second device are substantially coplanar; and/or a lowersource/drain portion of the first device and a lower source/drainportion of the second device are substantially coplanar.
 3. Thesemiconductor device according to claim 1, wherein, the U-shape of thefirst device comprises a first arm and a second arm opposite to eachother, and the U-shape of the second device comprises a third arm and afourth arm opposite to each other, wherein the first arm and the thirdarm extend oppositely in a substantially same direction, and the secondarm and the fourth arm extend oppositely in a substantially samedirection.
 4. The semiconductor device according to claim 3, wherein thefirst arm and the third arm extend along a substantially same straightline, and the second arm and the fourth arm extend along a substantiallysame straight line.
 5. The semiconductor device according to claim 1,wherein: an interface between the upper source/drain portion and thechannel portion of the first device and an interface between the uppersource/drain portion and the channel portion of the second device aresubstantially coplanar; and/or an interface between the lowersource/drain portion and the channel portion of the first device and aninterface between the lower source/drain portion and the channel portionof the second device are substantially coplanar.
 6. The semiconductordevice according to claim 1, wherein: an inner sidewall of the channelportion of the first device and an inner sidewall of the channel portionof the second device are substantially coplanar; and/or an outersidewall of the channel portion of the first device and an outersidewall of the channel portion of the second device are substantiallycoplanar.
 7. The semiconductor device according to claim 1, wherein: aninner sidewall of the upper source/drain portion of the first device andan inner sidewall of the upper source/drain portion of the second deviceare substantially coplanar; and/or an outer sidewall of the uppersource/drain portion of the first device and an outer sidewall of theupper source/drain portion of the second device are substantiallycoplanar.
 8. The semiconductor device according to claim 1, wherein: aninner sidewall of at least an upper portion of the lower source/drainportion of the first device and an inner sidewall of the lowersource/drain portion of the second device are substantially coplanar;and/or an outer sidewall of an upper portion of the lower source/drainportion of the first device and an outer sidewall of the lowersource/drain portion of the second device are substantially coplanar. 9.The semiconductor device according to claim 1, wherein the first deviceand the second device each further comprise a hard mask layer on anupper source/drain portion, wherein the hard mask layers of the firstdevice and the second device form a closed loop.
 10. The semiconductordevice according to claim 1, wherein the respective channel portions ofthe first device and the second device have a substantially samethickness along the U-shape.
 11. The semiconductor device according toclaim 10, wherein a thickness of the channel portion of the first deviceis different from that of the channel portion of the second device. 12.The semiconductor device according to claim 1, wherein the source/drainportions of each of the first device and the second device protrudestoward an inner side of the U-shape with respect to the channel portion,such that the source/drain portions and the channel portion are ofC-shape in a sectional view.
 13. The semiconductor device according toclaim 12, wherein a protruding extent of the source/drain portions ofthe first device with respect to the channel portion is substantiallythe same as a protruding extent of the source/drain portions of thesecond device with respect to the channel portion.
 14. The semiconductordevice according to claim 12, wherein an end portion of the gate stackclose to the channel portion is embedded in the C-shape.
 15. Thesemiconductor device according to claim 12, wherein the source/drainportions have a shape that tapers toward an inner side of the U-shape ina sectional view.
 16. The semiconductor device according to claim 1,wherein the U-shape has rounded corners.
 17. The semiconductor deviceaccording to claim 1, wherein for each of the first device and thesecond device, a distance between a doped interface between the uppersource/drain portion and the channel portion and an upper surface of anend portion of the gate stack close to the channel portion issubstantially the same as a distance between a doped interface betweenthe lower source/drain portion and the channel portion and a lowersurface of the end portion of the gate stack close to the channelportion.
 18. The semiconductor device according to claim 17, wherein thedistance is selected from 2 nm-10 nm.
 19. The semiconductor deviceaccording to claim 17, wherein the distance of the first device issubstantially the same as the distance of the second device.
 20. Thesemiconductor device according to claim 1, wherein a doping profile ofthe source/drain portions has an end portion overlapping the gate stack.21. The semiconductor device according to claim 1, wherein the channelportion of each of the first device and the second device is formed in afirst semiconductor layer, the first semiconductor layer verticallyextends to the source/drain portions such that each of end portionslocated at the upper and lower end constitutes a portion of acorresponding source/drain portion, and the source/drain portionsfurther comprise a second semiconductor layer and a third semiconductorlayer on the end portions of the upper and lower end of the firstsemiconductor layer.
 22. The semiconductor device according to claim 21,wherein the second semiconductor layer and the third semiconductor layerof each of the first device and the second device comprise a materialdifferent from the first semiconductor layer.
 23. The semiconductordevice according to claim 21, wherein a first semiconductor layer of thefirst device and a first semiconductor layer of the second device havedifferent materials and/or thicknesses.
 24. The semiconductor deviceaccording to claim 21, wherein the second semiconductor layer and thethird semiconductor layer of the first device comprise a materialdifferent from the second semiconductor layer and the thirdsemiconductor layer of the second device.
 25. The semiconductor deviceaccording to claim 21, wherein the third semiconductor layer is aportion of the substrate.
 26. The semiconductor device according toclaim 21, wherein the first semiconductor layer further comprises aportion extending laterally toward an outer side of the U-shape on thesubstrate.
 27. The semiconductor device according to claim 1, whereinouter sidewalls of at least an upper portion of the lower source/drainportion, of the upper source/drain portion, and of the channel portionof each of the first device and the second device are substantiallycoplanar.
 28. The semiconductor device according to claim 1, wherein thechannel portion and the source/drain portions comprise a single crystalsemiconductor material.
 29. The semiconductor device according to claim1, wherein, in a plan view, the gate stack is inside the U-shape. 30.The semiconductor device according to claim 29, wherein, in a plan view,the gate stack is throughout the inside of the U-shape.
 31. Thesemiconductor device according to claim 1, wherein the first device andthe second device have different conductivity types.
 32. Thesemiconductor device according to claim 31, wherein the first device andthe second device constitute a complementary metal oxide semiconductorCMOS configuration.
 33. The semiconductor device according to claim 31,wherein gate conductors in the gate stacks of the first device and thesecond device are in contact with each other and electrically connected.34. The semiconductor device according to claim 33, wherein a connectionsurface between the gate conductors of the first device and the seconddevice is biased toward the first device.
 35. The semiconductor deviceaccording to claim 31, wherein the first device and the second deviceare respectively formed on well regions of different conductivity typesin the substrate.
 36. The semiconductor device according to claim 31,wherein the first device and the second device comprise gate stackshaving different equivalent work functions.
 37. The semiconductor deviceaccording to claim 31, wherein: the first device is a p-type device, andthe source/drain portions thereof apply a compressive stress to thechannel portion, and the second device is a n-type device, and thesource/drain portions thereof apply a tensile stress to the channelportion.
 38. An electronic apparatus comprising the semiconductor deviceaccording to claim
 1. 39. The electronic apparatus according to claim38, comprising a smart phone, a computer, a tablet computer, a wearablesmart device, an artificial intelligence device, or a mobile powersupply.